Communication techniques based on electronic devices have been developed outstandingly, and approached toward physical limitations thereof, and there are attempts on complete optical communication using photons, which have excellent physical limitations over electrons, to fulfill ever growing communication demands.
There have been suggested several mechanisms for photonic packet switching, wherein it is important how to determine respective destinations of packets to be transmitted.
In addition, since there are speed limitations in the method for controlling the optical signal path using an electric signal, the studies have been performed on the method for determining directly the path of the optical signal with an optical signal using non-linearity of substance.
In general, previously suggested mechanisms for this depend on the third order non-linear susceptibility x.sup.(3) and, since a substance with both a large reduction rate and a large transparency to fulfill the general demand has not yet found, a switching device with large volume or an optical signal with strong intensity must be used and lights with two or more wavelengths must also be used.